I have tried this and it doesn’t fix the issue
I switched to ID Mobile on a 24 month contract with my old number ported.
I cannot log into WhatsApp, Ring, Blink, Life360, etc, which are all vital to me. Because the all require verification code sent as an SMS.
I’ve switched network and kept my number numerous times in the past -- this is a number I’ve used over 20 years. It has always been smooth with no exception. These networks include big ones like Vodafone, O2, Three, T-Mobile, Orange, and small ones like Giffgaff, Smarty, Lebera, Lyca.